kitchen sink drain is lower than waste pipe and leaks

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lafk

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hello. i am a home owner of a condo that is over 30 years old. i renovated my kitchen. the new sinks depth causes the drain pipe to be lower than the waste pipe. no matter what i have done (or had my uncle do) it stills leaks.

any advice on how to correct this?
thanks.
 

lafk

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thanks for your response

what does "working with tolerance of the fittings" mean? i took pics but could not upload b/c file was too big and i could not figure out how to make smaller.

there is not much waste pipe coming out of the wall to have altered or lowered. would the job entail adding new pipe to lower it?
 

Prashster

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I think you'd have to open the wall and lower that arm.

However, having a trap arm above the sink drain would cause the sink to back up and/or drain poorly. It shouldn't cause a leak. A leak is caused by a poor connection somewhere.

Of course, the high trap arm will exacerbate the leak bkz it cld cause standing water at the sink/drain connection.
 

Gary Swart

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Water will not flow uphill, so your sink will not drain properly until you lower the connection in the wall. This means you will have to open the wall and make whatever modifications to the drain necessary to achieve a downward slope from the sink trap to the drain. Your leak may be due to connecting the P trap arm at an angle into the drain, not assembling the arm properly, or both.
 

Geniescience

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i agree totally. The two problems are independent of each other.
- a leak is because of ... something in the installation (post a picture please), while
- a deeper sink may or may not require a lot of work in the plumbing in the wall.

Water only flows downhill. I guess in your case water does drain out of the sink (or else you would have mentioned this), so it may still be possible that the height of the trap arm going to the wall is just barely "not too high". But I'm not optimistic.

The way Gary Swart described it is a good way to think when you go look at it again. Starting from the P trap (the squiggly bendy part of the pipe under the drain), does the pipe going to the wall slope upwards at any angle? If so, one of the seals will leak somewhere. They are made to work when angles are flat 180 degrees.

Too bad you didn't make the whole countertop higher. People are building higher sinks and counters these days since we are all taller than a generation or two ago.

David
 

Prashster

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A lot of the pvc traps at big boxes are crappy and can easily cross threads, which'll affect the ability of the nut to adequately compress the plastic gasket - which can also be chinsy. I'm not saying to replace trap, just to be wary that it's finnicky has to be connected just so.
 

lafk

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here are some pics

hope this helps. thanks for your help. and thanks for the info on the dowload to make pics smaller.
 

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Gary Swart

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I think you may be able to fix these problems by redoing the P trap. In the first photo, it appears there is enough tailpipe coming out of the sink to allow the P trap to be raised toward the sink, but to do this you very well may have to shorten the tail pipe a bit. Next, replace that phony baloney flex pipe arm with a straight solid one. Shorten pipes as needed to fit Everything should be pretty close to straight lines, with the P trap setting just a tad higher than the drain. On longer drain lines, the minimum slope is 1/4" per foot, but you don't have to get that finite on a short run like this. Just make sure it's not going up. The plastic nuts should only be hand tight and you should use no Teflon tape or pipe dope on the threads.
 

Plumber1

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Just a note. I don't think that that black coupling is a drain fitting. It looks like its an offset reducing coupling. Looks like cast but could be malleable. Were sometimes used on heating systems.
 

Markts30

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To add to the above...
I agree that you will have to lower the drain in the wall and get rid of the corrugated flex...
As well, the reducing rubber fernco coupler is not approved for above ground...
Get rid of it and use a banded coupling or a proper waste and vent connector...
 

lafk

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thanks for everyones input

i will try some of the suggestions. lowering the waste pipe is that last resort. i dont know how this would be done. the waste pipe may lead into the condo next to mine. i dont know if it is shared. and there is not much pipe to play with as it has already been cut down since the sink was moved form the middle of the counter to the corner. i am trying to avoid getting a plumber to save money but may have to do so. i will let you guys know how it works out.
 

Jadnashua

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Since water doesn't flow uphill, I don't think you have much of a choice but to lower the connection in the wall. Where I live, on multi-family dwellings, it is illegal to do any plumbing unless you are licensed for liability problems - since your dwellings are connected, a change you make can seriously affect one or more of your neighbors and you wouldn't know it. Also, if the fittings aren't aligned fairly well, tension or torque can cause them to never get a good seal. I think you have a combination of the two since you normally would be able to make it watertight, but then still have a drainage problem.

Think it is time for a plumber...not that I like the idea when I'm pretty sure I could do the work myself, but there are times when it is much more efficient, and you know it will be done right. I think this is one of them.
 

Gary Swart

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If you can't raise the trap closer to the sink, then the only other choice is to lower the drain connection. A plumber would be the wise way to go because of the condo situation and because a plumber would do it right the first time.
 

Geniescience

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Gary Swart said:
If you can't raise the trap closer to the sink....
If the sink drain is higher than the pipe in the wall, you may be able to redo the P trap (e.g. by swapping the J bend's polarity) without opening the wall, as Gary has pointed out above and also six posts higher in this subthread.

The height of the garbage disposal drain is a big unknown from looking at your pictures.

david
 

Dubldare

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geniescience said:
If the sink drain is higher than the pipe in the wall, you may be able to redo the P trap (e.g. by swapping the J bend's polarity) without opening the wall, as Gary has pointed out above and also six posts higher in this subthread.

david



No, that's not how it's designed to work. Multiple reasons:

a)'spinning' the trap will deepen the trap seal, retarding flow and promoting fouling
b)the fitting where the j-bend meets the arm is required to be a ground joint, and is designed as such (an olive on the tube is a slip-joint, not a ground joint)
c)the fitting where the j-bend meets the arm cannot accept piping, which would make any attempt at using it as a slip-joint futile; as the integrity of the connection would be subpar, and would probably rattle off when the disposal was used, or when the wife puts the garbage can away
d)gravity is your friend, life is much easier when you remember that
 

Verdeboy

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Trap

I'm sure you guys will jump all over this. But here goes:

Assuming the drain pipe in the wall is pitched downward. Assuming that no water is leaking anywhere and that the sink drains fully, the plumbing under the sink becomes an "extended trap." If it is necessary and desirable to have a standard trap, why is it so horrible to have a slightly larger trap?
 
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